The invention relates to a flow regulation control valve for setting and measuring volume flows in pipes, in particular in pipes of supply systems. The invention makes it possible for an actual state of a volume flow to be recorded with the aid of measuring instruments with evaluation and display devices and for a desired state to be set by means of a control member of the valve.
Piping systems distribute a conveyed medium to individual usage points within a building or in a plant. Such piping systems usually have a large number of branches, and there is the problem of guaranteeing a supply which meets the respective demand under full load at the individual usage points. The ability to make an adjustment is needed for the most unfavourable operating state of a piping system, in which all the users demand the maximum supply at the same time. In this case, the supply to the users, for example heat exchangers, should neither be insufficient nor excessive. For this purpose, it is known to adjust the individual pipe sections accordingly.
Flow regulation control valves which are fitted with connections for pressure-measuring lines are useful for this purpose. A separate pressure-measuring device which can be connected thereto measures the differential pressure inside the valve between two measuring points which are spaced apart from one another. There is usually also a shut-off member for the flow control valve located between the two measuring points. After the differential pressure has been measured, the instantaneous volume flow is determined with the aid of existing specific characteristic values of the valve and knowledge of the position of the shut-off member relative to the associated seat. By changing the position of the shut-off member, the volume flow is changed in order to establish a desired volume flow by means of further measuring and control operations. Such valves for section control are known from the publications DE-C 40 30 104, EP-A 0 671 578 and WO 92/03677.
This kind of section control is very time-consuming and cumbersome, and it is even more awkward to carry out in the case of large and branched pipe sections. In this context, it is also known use measuring computers to convert the differential pressures measured in section control valves into the respective throughflow volumes. For this purpose, the specific data of a valve must be stored in the measuring computer. To do so, it is also absolutely essential to know the momentary position of the shut-off member in relation to the associated seat. Changing the position of the shut-off member causes a change in the throughflow volume. Depending on the construction of the valve, the respective stroke or rotational position of a shut-off member of a flow regulation control valve must be recorded by the operator and, in addition, entered manually into the measuring computer.
Although such flow regulation control valves permit an exact setting of the throughflow volumes in different pipe sections, they also have many disadvantages. There is the risk of the measuring bores in the housing becoming soiled. Considerable measuring errors may occur if the necessary pressure-measuring lines have not been vented with extreme care. Furthermore, the assembly and the disassembly of the measuring lines at the pressure measuring points of a pressurized housing in which high temperatures and/or pressures can prevail constitute a great potential hazard. To avoid inaccuracies in the measurements which result due to the occurrence of eddies inside the housing which have adverse effects on the measuring parameter, sufficiently long settling routes are usually required in front of and behind the measuring points in order to assure sufficient measuring accuracy. The handling of the overall measuring device is also very awkward.
Another type of adjustment of pipe sections is known from the product TACO-SETTER, which is published in the catalogue of the company Gebrxc3xcder Tobler AG, Haustechniksysteme, CH-8902 Urdorf, 1994 edition, pages 2.59 and 2.60. This is a throughflow measuring device which can be inserted directly into a piping system and has an integrated fine control valve. The throughflow volume displayed by the throughflow measuring device can be changed with the aid of the fine control valve. However, this solution has the disadvantage that its use is limited to clean liquids. Due to the mechanical construction of this throughflow measuring device, periodic servicing and additional monitoring outlay are required. In the case of soiled media, incorrect measurements are therefore to be expected. Additionally, such a throughflow measuring device which is installed directly in the flow path also changes the flow resistance in the piping system. Attempts have been made to avoid the latter disadvantage by arranging the throughflow meter in a bypass line around a shut-off valve. Although this solution improves the operability, it brings about a reduction in the measuring accuracy.
A sensor in the form of a pressure monitor with integrated temperature measurement is known from FR-A-2 713 764. This sensor, which is to be installed in a pipe, has a diaphragm which reacts to changes in pressure. If stipulated threshold values are exceeded, a switch-on or switch-off signal is emitted. With the aid of the temperature recording device, the presence of a flow is also determined at the same time and is displayed with the aid of additional devices.
DE-A 34 32 494 discloses a regulating and/or control arrangement for regulating or controlling the throughput of gas or liquid flows in pipelines. This device is intended to permit flexible configuration of industrial or technical plants to facilitate changes or expansion. The solution proposed for this provides for the actuating element, the actuator, the sensor and the control device to be combined into one structural unit and for it to be possible for this unit to be inserted as such into the pipeline. This collection to form a single structural unit is intended to permit easier installation at the suitable point in a pipeline. By comparison with the previous regulation systems, which were constructed from discrete components and require more space, the simpler connection technique of the individual components, which are accommodated in a single housing and are fed by a common power supply, is an advantage. According to FIG. 1, however, this actuating unit has a considerable overall size. It must be constructed to be at least sufficiently large to be able to accommodate a three-way valve, parts of the pipelines connected to the three-way valve and a relatively long pipeline section in which a sensor is arranged at a distance from the three-way valve. The sensor has to be arranged at a large distance from the three-way valve in order for the pipeline section, which acts as a quieting section, to be able to balance out the flow turbulence which occurs within the valve. The document is always concerned only with a sensor which is used in a pipeline and which, depending on its construction, can record different physical, chemical or biological states of a medium.
The actuating unit, which is configured on the building-block system, can always be fitted with only one sensor, it having to be ensured that the control variables output by the various sensors which can be used are compatible with the input signal values of a control device. In addition to the control variable input to the control device from the replaceable sensor, there is a further permanently arranged sensor as a temperature sensor. Since in many applications the temperature constitutes an interfering variable and can impair a regulation process, the interfering variables output by the permanently installed temperature sensor, and the controlled variable supplied by the replaceable sensor, which is in contact with the conveyed medium, are conditioned in the control device and processed to form an activating signal in which the interfering variable has been compensated for.
This solution, in the form of an autonomous, decentralized intelligence, has a very large overall volume and can therefore be used only in large process plants. The construction as a structural unit certainly permits simpler installation but constitutes a structure which is difficult to handle because of the multi-way valve and the pipeline which functions as a collecting line, together with the sensor which is installed therein at a distance from the multi-way valve, arranged within a common housing. The spacing due to the pipeline between the valve and the sensor is functionally necessary to be able to obtain reliable measurements. This is because in order to be able to obtain a reproducible measured signal, in this solution the sensor must be arranged to be separated from the valve by the pipeline section which serves as a quieting section. Turbulence arising in the valve housing is compensated therein on the way to the sensor.
Additional overall volume is necessitated by an actuating motor for the valve, likewise arranged within the housing, a gear mechanism, an end-position sensor for detecting the end positions of the closure member of the actuating element, as well as an additional temperature sensor for eliminating temperature changes as interfering variables.
The so-called inductive throughflow measuring devices are, for example, very precise and contactless without causing any additional flow resistance. Since they are very expensive, they are usually only used for short times for adjustment at a measuring location. This necessitates great expenditure in the form of shutting down the plant, emptying the plant and installing and dismantling the measuring device, and subsequently starting up the plant. If the construction of a plant is changed, repeat measurements are required, entailing equally great expenditure.
It is the object of the invention to provide a simple possibility of adjusting pipe sections, with the aid of which a volume flow can be adapted in a less complex manner to the respective conditions of the pipe.
The solution to this problem envisages that a sensor which directly or indirectly records the volume flow of the flow chamber is arranged in the region of the flow chamber, that specific characteristic values of the section control valve are stored in an electronic data store, and that an evaluation unit determines the volume flow from the values measured by the sensor and from the characteristic values of the data store. It can usually be assumed that the sensor is located at an installation site with constant or reproducible flow conditions in the inflow region of the valve housing. Existing shut-off valves, preferably lift valves with good throttling properties, can thus be used in a simple manner as flow regulation control valves at the same time. Flow regulation control valves with special measuring bores which are of complicated design and manufacture and the risks involved with the connection of measuring lines can be dispensed with. It is sufficient for the manufacturer to integrate a sensor into a housing of a shut-off valve, the surface of the sensor being at least flush with the flow chamber or protruding slightly into the latter. The volume flow can thus be measured without having a disturbing effect on the flow. For this purpose, a measuring parameter is used which is provided by the sensor and is proportional to the volume flow. The dependency of this measuring parameter on the volume flow prevailing in the valve is preferably determined by means of a calibration operation. Other methods, for example calculatory methods, may also be used for determining the relationship of the measuring parameter to the volume flow. The sensor remains permanently in the housing and is arranged in a sealing manner therein. Thus, if such a flow regulation control valve is used, it is no longer necessary to intervene in the pressure-conducting piping system when there is a demand. Depending on the construction, the volume flow could be read from the evaluation unit directly or after setting up a data connection. This can be done without difficulty and poses no risk to the operator or the environment.
According to a further solution to the problem, the flow chamber of the flow regulation control valve is operatively connected to the flow chamber of a separate flow housing, a sensor which directly or indirectly records the volume flow of the flow chamber is arranged in the region of the flow chamber of the separate flow housing, and specific characteristic values of the flow regulation control valve constructed as a structural unit are stored in an electronic data store, and an evaluation unit determines the volume flow from the values measured by the sensor 6 and from the characteristic values stored in the data store.
This enables a standard shut-off valve to be converted to a flow regulation control valve in a simple manner. The arrangement of the flow housing containing the sensor in the immediate vicinity of the shut-off valve makes it possible to manufacture a flow regulation control valve as a modular unit which is easy to assemble. A flow regulation control valve which is manufactured as a modular unit in this way merely requires a single calibration in order to be able to measure the flow-related operational condition. The flow-related operational condition is influenced by a change in the position of the control and/or shut-off member. The calibration of the modular unit satisfies the precondition in order to be able to carry out expedient measurements with the aid of the sensor. Compared to volume-flow measuring instruments which have to be installed in a pipe separately, the flow regulation control valve configured and calibrated as a modular unit results in a considerable shortening of the construction length. This is because this overall arrangement can dispense with a settling route between the separate flow housing and the flow regulation control valve, which settling routes are absolutely essential for settling the flow to be measured between commercially available volume-flow measuring instruments and flow regulation control valves.
For example in existing piping systems, so-called old plants, this permits shut-off valves with a long valve construction length to be replaced by a section control valve which comprises a modular unit constructed of a compact valve of short length and a separate flow housing with an integrated sensor. Using adapters which may be necessary to compensate for the difference in the construction lengths, installation is possible without changing the existing pipe.
The sensor employed converts the physical parameter to be measured and changes therein into an electrical parameter and changes therein, which can be further processed or transmitted electronically. Depending on the construction of the sensor and the degree of integration and/or miniaturization employed, both signal preparation and signal processing can be incorporated in the sensor.
A refinement of the invention envisages a sensor which operates according to the calorimetric measuring principle. Depending on the valve housing employed, an installation site is selected for the sensor, at which reproducible flow conditions prevail within the relevant throttling range, which flow conditions are independent of the position of the shut-off body relative to its seat. This is the case in a simple manner on the inflow side of a flow-conducting housing, especially in the region of the entry flange, particularly displaced by 90xc2x0 relative to the spindle axis. It is thus no longer necessary in order to determine the volume flow to record the position of the shut-off body in relation to its seat. The relation between the measured signal and the volume flow is determined, for example, experimentally by means of a calibration operation.
If valves are employed which due to their shape give rise to difficult flow conditions, a plurality of sensors can be used. These are then arranged distributed around the circumference in the region of the flow cross-section to be measured. For such applications, the volume flow is determined by forming an average value from the values measured by the individual sensors.
A further refinement of the invention envisages that the sensor in the wall of the flow chamber is at least flush with the surface or protrudes with a slight projection into the flow chamber. This measure guarantees, on the one hand, reliable recording of the volume flow which is reproducibly related to the measuring signal. On the other hand, any increase in the resistance coefficient of the valve thus caused is negligible.
According to a further refinement of the invention, the evaluation unit may be connected to the sensor either directly or via connecting means. The evaluation unit can thus be mounted as a compact, highly integrated unit directly on the sensor or with the interposition of connecting means on the valve. The volume flows prevailing at a given moment in the valve can be read off directly with the aid of display devices. Depending on the construction of the evaluation unit, this could take place continuously or only when there is a demand.
According to a further refinement, the characteristic values specific to the valve housing are contained in the electronic data store in the form of a table, in the form of a characteristic curve or as an algorithm. If the sensor is, for example, integrated into a flange of a valve housing and is fitted with its own electronic data store, flow regulation control can take place in a very simple manner. The characteristic values typical of a specific housing are stored permanently in the installed sensor. Every sensor can be calibrated by the manufacturer in accordance with its specific installation site. In order to adjust a plant precisely, an evaluation unit must be connected to the sensor. Based on the measured parameters provided by the sensor and in conjunction with the associated characteristic values, the desired volume flow can be adjusted quickly and without difficulty in a very simple manner with the aid of the evaluation unit. For this purpose, the position of the shut-off member merely has to be changed manually or automatically depending on the design. It is not necessary to input an additional calculation variable, e.g. the position of the shut-off body. When setting up a calibration curve, the associated measurements for several and different preset volume flows within the relevant volume flow range of the respective housing are recorded and associated. Inaccuracies are thus compensated; the result is more precise and savings can be made compared to the previous partially manual and calculatory outlay. The data can be stored in the electronic data store as a characteristic curve, table, algorithm or in another known form. It is also possible to determine and display the mass flow from the volume flow with the aid of known means.
Further refinements of the invention are described hereinafter. Accordingly, the electronic data store can contain the characteristic values for a specific housing in the form of a table, in the form of a characteristic curve or as an algorithm. Depending on the type and construction of the electronic data store used, the characteristic values typical of the specific valve can be stored in a form which permits unproblematic read-out by means of an evaluation unit and the computing elements located therein. The data store may also be integrated into the sensor or into the evaluation unit. The data store may likewise be arranged partially in the sensor and partially in the evaluation unit, with the data store integrated into the sensor containing at least one valve recognition signal. Furthermore, in addition to a microcontroller, the evaluation unit contains a voltage supply which can be configured as a connection to an external apparatus or is present as an internal apparatus in the form of batteries, accumulators or the like. Additionally display devices, operating elements and the necessary connection elements may be included.
The adjustment of the flow through a section takes place by means of simply adjusting the shut-off member of the flow regulation control valve until the desired volume flow is displayed in the evaluation unit. Depending on the requirement, the evaluation unit may be configured as a permanently installed component or as a mobile device. The connection between the evaluation unit and the respective sensor can be made using conventional connectors. These may be permanent or releasable connections or wireless communication means, such as infrared transmission, radio waves and the like.
Other refinements of the invention envisage that a data store with a small storage capacity integrated into the sensor contains a valve recognition signal, and that an electronic data store located in the evaluation unit contains characteristic values of the valve in characteristic curves or in the form of a table.
In this case, the evaluation unit will contain a considerably larger electronic data store with all the characteristic values of the valves which can be adjusted therewith. The small data store of a sensor then contains only a code identifying the particular flow regulation control valve in which it is installed. When the sensor communicates with the evaluation unit, the corresponding valve data is read out from the larger store of the evaluation unit based on the respective identification code and is made available for processing. Customary storage media may be used as electronic data stores.
With the aid of one or more interfaces which can be connected to a bus system, the values measured by the sensor and the respective characteristic curves of the assigned housing can also be transmitted to a central control or switching point. By means of the data exchange via the interfaces, the data or the measured values can be exchanged with a central control or switching point or with other elements of the piping system.
It is also possible to integrate a display into the evaluation electronics which directly displays the current volume flow based on the measured variables recorded by the sensor. In order to minimize the constructional expense, the sensor is configured as a passive element whose voltage supply is provided via the evaluation unit. In this case, known energy sources can be employed.
Furthermore, an element may be integrated into the sensor, with which the temperature of the medium located inside the housing can be recorded. This value can also be displayed directly on the display of the evaluation unit.
A further advantage can thus be achieved in a very simple manner by the fact that the heat output transported inside the pipes and/or the heat consumption are calculated and displayed. The heat output present in piping systems can be calculated from the measurement or calculation of the temperature difference, for example between the forward flow and return flow, and the volume flow. Only an additional time measurement is required to calculate the heat consumption. The measured and calculated values required and additional structural and operational elements can be integrated into the evaluation unit or into a central control point. The sensors can also be connected to such a control point by means of appropriate connection lines.
A major advantage of this invention is that the respective volume flow and the momentary medium temperature can be read directly at the flow regulation control valve without any further manual effort. The additional throughflow measuring instruments for the pipe previously required for this purpose are dispensed with as is the awkward pressure-loss measurement, which required additional hose connections to a flow regulation control valve. The expenditure for the respective adjustment is thus reduced considerably and a saving in space is also possible at the same time. Integrating the sensor into an ordinary shut-off valve or into a separate flow housing which interacts therewith does not change its shut-off function, and the use of a special flow regulation control valve with the problematic connection lines for the recording of measurement data can be dispensed with.
The evaluation unit also permits a desired value of the required volume flow to be input directly into the evaluation unit during an adjustment operation. With the aid of the transmission means between the evaluation unit and the sensor, this desired value can be stored in the data store of the sensor. Depending on the construction of the plant, it is possible to establish in a very simple manner, with temporary or permanent monitoring by means of a target value/actual value comparison, whether there is any discrepancy. If this were to be the case, a readjustment could be carried out by actuating the valve. The control mechanism may be a customary handwheel, a hand lever or an adjusting motor. A readjustment can be carried out in a very simple manner due to the possibility of direct visual recording of the momentary volume flow on a display and without the additional outlay in terms of measuring equipment to record the location or position of the shut-off members. If the evaluation unit, which can be used in a stationary or mobile manner, were to be arranged permanently on a housing to be monitored, the manner of attachment is selected so as to allow a display irrespective of the position in which the housing to be monitored is installed.
Illustrative embodiments of the invention are shown in the accompanying drawings, and are described in greater detail below.